Actuators actuated with pressurized media are increasingly used in motor vehicles and make the operation of such vehicles safer and easier. Such vehicle systems supported by auxiliary power are, for example, steering boosters, power assist brake units, and clutch actuation devices. Pressurized media is required for operating these actuators, which may be configured, for example, as piston-cylinder arrangements, where the media can be gas or hydraulic fluids. A mechanically or electrically driven hydraulic pump supplies, during operation, such media at an operating-pressure level which suffices for producing the required actuator forces.
A known method of minimizing the negative influence on fuel consumption of vehicles equipped this way is supplying the media to an accumulator, at a sufficiently high actuating-pressure, by means of the hydraulic pump. Since the use of the media pressure in the affected actuators typically occurs discontinuously, the hydraulic pump is only activated by means of the known control devices and/or control methods when the pressure in the accumulator has dropped below a predefined lower-pressure threshold. This lower-pressure threshold is still above the required actuating-pressure for the aforementioned actuators, so that their operation is guaranteed even during such a pressure-charging phase. The hydraulic pump is turned off when a predefined upper-pressure threshold has been reached. A hydraulic pressure system configured in this way is known, for example, from DE 198 30 089 A1.